CN201375701Y disclosed a true sense massaging breast pump wherein the breast pump has a silica gel liner capable of shrinking and expanding automatically during milking, such that the user would not suffer from breast distending pain and feel comfortable. The disclosed breast pump comprises a pump unit, a breast cup, and a silica gel inner lining, wherein a threaded adaptor is mounted on an upper end of the pump unit and an air vent is provided on the breast cup, with the rear end of the breast cup provided with a threaded hole for coupling with the threaded adaptor. A baffle ring is provided in the threaded hole to cooperate with a flange provided to the bottom of the inner lining. The side walls of the inner lining abutting against breast have a corrugated shape. The disclosed breast pump has a disadvantage of an absence of functions of massaging breast, stimulating areola, and pressing teat cistern during pumping due to the presence of the air vent provided on the cup. In this case, frequent using would cause uncomfortable sensations such as breast ache, inflamed nipple, and breast deformation. The disclosed breast pump has no differences in this respect from conventional breast pumps.
PCT/NO2003/000436 described a manual breast pump comprising a breast cup, a pump housing with a piston and an activation mechanism in the form of a handle, together with a container, preferably in the form of a bottle for collection of the milk. The breast cup comprises a preferably rigid outer part and an inner, preferably completely or partially flexible, part, where two mutually separate chambers are provided between the outer part and the inner part. The piston comprises a membrane that connects the periphery of the piston with the wall of the pump housing and thereby divides the pump housing into an upper chamber and a lower chamber. The upper chamber is in liquid contact with the chambers of the breast cup with the help of two openings with associated tubes and the lower chamber is in liquid contact with the inside of the breast cup. The described manual breast pump has a disadvantage that the breast cup has no action in use and a negative pressure will be generated inside the interior of the breast cup during milking, so as to press the breast to milk, causing breast distending pain.
PCT/IB2005/000044 disclosed a breast pump comprising: a housing having a funnel portion, said funnel portion comprising an outer funnel and an inner funnel received in said outer funnel and said inner funnel defining a funnel interior adapted to sealablely engage a breast; at least one flexible membrane formed in the inner funnel; a chamber defined by an inside wall of said housing, said chamber adapted to receive a pressure generating mechanism and having a vacuum port in fluid communication with said funnel interior and having a pressure port; a pressure conduit in fluid communication with said pressure port and said membrane; wherein during a stroke of said pressure generating mechanism a negative pressure is conveyed to said funnel interior and a positive pressure is conveyed to said pressure conduit to displace said flexible membrane. The breast pump disclosed is capable of massaging the breast while milking. However, the complicated structure of this type makes the breast pump difficult to assemble and clean, non-cost effective, and possibly forms rust.